Methane-thiol containing nematocides



dollars.

3,255,075 METHANE-THIOL CONTAINING NEMATOCIDES Max J. Fielding,Wilmington, Del., assignor to E. I. du Pont de Nemours and Company,Wilmington, Del., a corporation of Delaware No Drawing. Filed Mar. 29,1963, Ser. No. 269,143 3 Claims. (Cl. 16722) This invention relates tonematocidal compositions and methods.

More specifically, this invention refers to a method of killing plantpathogenic nematodes by applying to said nematodes a mercapto-terminatedthiomethylene compound.

Plant nematodes are found in virtually all soils in which plants willgrow. Consequently, every major crop is a potential victim of this pest.The annual toll on crops in the United States is well over severalhundred million A practical commercial chemical is needed to stop thisunnecessary loss. However, in order to be commercially practicable achemical must be non-toxic to animals and plants and kill a broadspectrum of nematodes at low rates.

I have discovered that the following compounds qualify as effectivecommercial nematocides:

Methanedithiol,

Thiodi (methanethiol) Methylenedithiobis(methanethiol) andThiodimethylenedithiobis (methanethiol) Although all of the abovecompounds kill nematodes, particularly outstanding results are obtainedfrom thiodi- (methanethiol), methylenedithiobis(methanethiol) andthiodimethylenedithiobis (methanethiol) The most highly preferredcompound because of its outstanding activity at low rates isthiodi(methanethiol).

Acceptable nematocidal treatments are obtained from a mixture of two ormore of all the above compounds.

PREPARATION Methanedithiol is prepared in the manner described by Cairnset al., J. Am. Chem. Soc., 74, 3982 (1952). Thiodimethanethiol is formedalong with methanedithiol in the reaction between hydrogen sulfide andformaldehyde and may be separated by distillation.Methylenedithiolbis(methanethiol) and thiodimethylenedithiobis(methanethiol) are prepared by the process described in Saegebarth, US.Patent 3,056,841.

COMPOSITION Compositions of this invention comprise one or more of thecompounds described above together with one or more surface-activeagents.

The surface-active agents used in this invention can be a wetting,dispersing or an emulsifying agent which will assist dispersion of thecompound. Surface-active agents or surfactants can include such anionic,cationic and nonionic agents as have heretofore been generally employedin plant control compositions of similar type. Suitable surface-activeagents are set out, for example, in Searle US. Patent 2,426,417; ToddUS. Patent 2,655,417; Jones 3,255,075 Patented June 7, 1966 ethylenethioethers and long chain quaternary ammonium chloride compounds.

Surface-active dispersing agents such as sodium lignin sulfonates, lowviscosity methyl cellulose and polymerized sodium salts of alkylnaphthalene sulfonic acids are also suitable in the nematocidalcompositions of this invention. Among the more preferred surfactants arethe anionic and non-ionic types. Among the anionic surface-activeagents, preferred ones are alkali metal or amine salts of alkyl benzenesulfonic acids, such as dodecylbenzenesulfonic acid, sodium laurylsulfate, alkyl naphthalene sulfonates, sodium N-methyl-N-oleoyltaurate,oleic acid ester.

of sodium isethionate, dioctyl sodium sulfosuccinate and sodiumdodecyldiphenyloxide disulfonate. Among the non-ionic compounds,preferred members are alkyl phenoxy poly(ethyleneoxy)ethanols such asnonyl phenol adducts with ethylene oxide; also preferred are trimethylnonyl polyethylene glycol ethers, polyethylene oxide adducts of fattyand rosin acids, long chain alkyl mercaptan adducts with ethylene oxideand polyethylene oxide adducts with sorbitan fatty acid esters.

In general, less than 10% by weight of the surfaceactive agent will beused in compositions of this invention and ordinarily the amount ofsurface-active agents will range from 0.5 to 5% by weight.

Nematocidal compositions of this invention can also contain finelydivided inert diluents, such as talcs, natural clays, includingattapulgite clay and kaolinite clay, pyrophyllite, diatomaceous earths,synthetic fine silicas, calcium silicate, carbonates, calciumphosphates, lime, and such flours as walnutshell, wheat, redwood,soybean and cottonseed flour. i

The amount of the finely divided inert solid diluent can vary widely butwill generally range from 1 to 50% by weight of the nematocidalcomposition. Compositions of from 2 to 30% active ingredient arepreferred. The particle size can vary considerably but will ordinarilybe somewhat under 50 microns in the finished formulation.

A preferred formulation contains from about 10 to 50% by weight of amercapto-terminated thiomethylene, a total of 45 to 89% by weight ofsolid diluents and 1 to 5% by weight of one or more surfactants.

Although the compounds used in this invention are normally liquids, itis possible to formulate them into dusts for direct application or intowettable powders which are applied in a slurry. In the case of wettablepowders, surfactants and diluents are usually both present in thenematocidal composition.

It [is sometimes also advantageous to formulate the nematocidal compoundof this invention as granules or pellets, for example by applying theactive ingredient to preformed clay granules, such as granularattapulgite, or to'granular vermiculite. Usually, such granules willcontain 1 to 10% by weight of the active ingredient, although forspecial uses as much as 15 to 20% by weight can be applied.

Emulsifiable oil solutions can be employed with one or more of themercapto-terminated thiomethylenes used in this invention. In thesenematocidal compositions, the surface-active agent and the oil form aliquid which can be conveniently poured and measured. Such solutions canbe mixed with water at the point of application to form an emulsioncontaining the nematocide and the solvent. Such compositions have theadvantage that the oil will often act as a foam inhibitor and thusreduce the tendency for large amounts of surfactants to formobjectionable foam. The oil used such as toluene,'kerosene, stoddardsolvent, xylene, alkylated naphthalene, diesel oil and the like shouldbe preferably water immiscible and be of a type in' which the activeagent will be soluble in the amounts used in particular formulations.Other solvents, such as chlorinated hydrocarbons liketetrachloroethylene,

- 4 to 8 inches.

ketones like cyclohexanones, cellosolves, N,N-dialkylamides, carbitols,and the like can also be used, either alone or in admixture with thehydrocarbon solvents shown above.

In the above emulsifiable oil concentrates, the mercapto-terminatedthiomethylenes will be present in amounts ranging from 5 to 80% byweight, to 35% by weight being a preferred range. Precise concentrationsof active agent, of course, will depend on the intended use of thecomposition. When mixed with water at the point of application the oilconcentrate will be diluted so that in the final spray emulsion theactive agent will be present in amounts ranging from 0.5 to 2% byweight.

A formulation that I have found to be especially advantageous in theapplication of mercapto-terminated thiomethylenes to nematode infestedsoil is a composition containing from about 20 to 80% by weight ofmercaptoterminated thiomethylenes, from about 17 to 75% by weight of oneor more inert liquid diluents and from about 0.5 to 8% by weight of oneor more surface-active agents.

APPLICATION As a practical matter application rates of from 2 to 100pounds of active mercapto-terminated thiomethylenes per treated acre ofsoil are satisfactory for nematode control, although higher rates can beused. The active mercapto-terminated thiomethylene, preferably in asuitable formulation as described above is applied to the soil by anyconventional method such as spraying or dusting by hand or mechanicalequipment. After application, the composition is worked into the groundto a depth of about Spot shanking into an open furrow is a particularlyadvantageous method of application.

The compounds used in this invention are also applied to nematodeinfested plant material, such as bulbs, tubers, or roots of ornamentalplants and nursery stock. Disinfection is carried out by. dipping thebulb, tuber or plant root into a solution or suspension containing 5 to50,000 p.p.m. of one or more active mercapto-terminated thiomethylenecompounds.

An application to a locus of infestation includes the treatment of soil,plant material, before or after planting, and other sites infected withadult nematodes, their eggs or larvae.

The active compounds used in the invention can be advantageously mixedwith soil fungicides such as p-Dimethylaminobenzenediazosodiumsulfonate;

Quinone oxyaminobenzooxohydrazone;

Tetraalkyl thiuram sulfides such as tetramethyl thiuram monosulfide ordisulfide and tetraethyl thiuram monosulfide or disulfide;

Metal salts of ethylene bisdithiocarbamic acid, e.g.

Manganese, zinc, iron and sodium salts;

Pentachloronitrobenzene;

Dodecylguanidine acetate;

N-trichloromethylthio tetrahydrophthalimide (captan);

Phenylmercury acetate;

2,4-dichloro-6-(o-chloroanilino)-s-triazine N-methylmercuryp-toluenesulfonanilide;

Chlorophenol mercuri hydroxide;

Nitrophenol mercuri hydroxides;

Ethel mercury acetate;

Ethyl mercury 2,3-dihydroxypropyl mercaptide;

Methyl mercury acetate;

Methyl mercury 2,3-dihydroxypropyl mercaptide;

3,3'-ethylenebis(tetrahydro-4,6-dimethyl-2H-1,3,5-thiadiazine-2-thione)Methyl mercury dicyandiamide;

N-ethyl mercury-p-toluenesulfonanilide;

Metal (e.g. iron, sodium, and zinc), ammonium and amine salts ofdialkyldithiocarbamic acids;

Tetrachloronitroanisole;

Hexachlorobenzene;

The above fungicides are added to compositions containing amercapto-terminated thiomethylene at the rate of 1 to 400 pounds to each20 pounds of a compound Within the scope of this invention. Illustrativeof fungicides used at low rates with the mercapto-terminatedthiomethylenes are the above-described organo mercurials. Illustrativeof fungicides used at high rates with the mercapto-terminatedthiomethylenes are thiuram sulfides and captan. Of course, more or lessof the above-listed fungicides can be added to a composition of thisinvention depending on the fungi present in the area to be protected.

Compositions of this invention can additionally contain soilinsecticides such as chlordane, DDT, dieldrin, endrin, aldrin,methoxychlor and others for simultaneous application of nematocide,fungicide and insecticide to the soil.

In addition compositions can contain special additives such as corrosioninhibitors, pigments, antifoam agents and the like.

The compounds used in this invention can also be applied, mixed or incommon solution with other chemicals which are used in agronomic andhorticultural management and are compatible with the compounds used inthis invention. Such chemicals can be but are not restricted to theclasses of chemicals commonly known as plant nutrients,fertilizers,herbicides and other nematocides.

The following additional examples in which all percents unless otherwiseindicated are by weight are provided to more clearly explain thisinvention.

Example 1.-Pre.parati0n of methanedithiol and thi0di(methanerhi0l) Arocker bomb is charged with 120 parts by Weight of paraformaldehyde and544 parts of hydrogen sulfide. The bomb is closed and heated withagitation at 8090 C. for 12 hours. The bomb is cooled, excess hydrogensulfide vented and the two phases'separated.

The upper aqueous phase is extracted with ether. The ether extract andthe lower organic phase are combined, dried with magnesium sulfate anddistilled through a column. This distillation produces 90 parts ofmethanedithiol, boiling point 43 C. at 44 mm., and 104 parts ofthiodi(methanethiol), boiling point 57 C. at 0.85 mm. The nuclearmagnetic resonance spectrum of thiodi(methanethiol) on Varian A-6O NMRSpectrometer using tetramethylsilane as an external reference showsthree bands at delta =-2.57, 2.70 and 2.84 p.p.m. assigned to the twothiol hydrogens and two bands at delt-a=4.23 and Example 2.Preparati0n 0methylenedithiobis(methanethiol) andlhiodimethylenedithiobis(methanethiol) A steel bomb is charged with 284parts by weight of 37% formalin solution. About 225 parts of hydrogensulfide is distilled into the bomb after it is chilled and evacuated.The bomb is then sealed and heated at 60 C. for 4 hours. The reactionvessel is cooled, the excess hydrogen sulfide vented, and the lowerorganic phase of the two phase reaction mixture is separated. Thisliquid intermediate (220 parts) is stirred under nitrogen with .150parts concentrated hydrochloric acid and 300 parts water at C. for 6hours. The lower organic layer is separated, washed with water and driedover magnesium sulfate. The largest constituent of the resulting oil ismethylenedithiobis(methanethiol). A lesser constituent isthiodimethylenedithiobis(methanethiol). Thiodi(methanethiol) is alsopresent in variable amounts. This crude mixture is satisfactory for thenematocidal compositions and methods of this invention.

Ifdesired, the active components of the reaction mixture can beseparated by distillation. Thiodi(methanethiol) distills off first,boiling point 57 C. at 0.85 mm., followed bymethylenedithiobis(methanethiol), boiling point approximately 110 C. at0.1 mm.

- Example 3 Percent Thiodi(methanethiol) 25 Dioctyl sodiumsulfosuccinate 1 Sodium lignin sulfonate 2 Attapulgite clay 45 Syntheticfine silica 25 These materials are thoroughly blended to prepare auniform mixture. The mixture is then ground in a micropulverizer untilthe particle size is substantially less than 50 microns.

This 25% wettable powder formulation, when dispersed in water, isapplied with conventional spray' equipment at a concentration of aboutlO'pounds wettable powder to gallons of water at a rate between to 100pounds active ingredient per acre to land infested with plant pathogenicnematodes. After spraying onto the surface of the soil, the chemical ismixed in the soil to a "depth of 4 to 6 inches with a rotovator.

When soil infested with root-knot nematode, Meloidogyne, is treated inthis way, cotton plants grown show normal development free from nematodeinfection. Plants grown in similar non-treated soil show stunting, andreduced yields due to nematode infection.

Example 4 Percent The crude reaction product of Example 2, containingmethylenedithiobis(methanethiol), thiodi(meth- These materials arethoroughly blended in a ribbon blender, and ground in a micropulverizeruntil the particle size is substantially less than 50 microns. Theresulting wettable powder formulation can be diluted with water to thedesired spray concentration.

This formulation is suspended in water, and drenched about the roots ofboxwood plants infected with the spiral nematode (Helicotylenchusbuxophilus) at rates of 50 to 200 pounds active agent per acre, usingenough water to wash the active agent down about the plant roots.Substantially all spiral nematodes are killed by this treatment,allowing the boxwood plant to develop in a normal manner.

Example 5 Percent The crude reaction product of Example 1 30 Blend ofpoly-alcohol carboxylic esters and oilsoluble sulfonates 6 Alkylatednaphthalenes 64 The above ingredients are blended until a completelyhomogeneous mixture is obtained. The resulting emul sifiable compositioncan be extended with water to the required concentration for spraying.

The above emulsifiable concentrate is diluted with water and sprayed atthe rate of 60 pounds per acre of active ingredient in 120 gallons ofwater on a field infested with sugar beet nematode (Heteraderaschachtii) and the chemical is worked into the soil to a depth of 6inches. Sugar beets grown in this field develop normally and aresubstantially free from infestation by nematodes. In an untreated areain the same field, beets are distorted and yields reduced.

Example 6 Percent Methylenedithio-bis(methanethiol) 75 Nonyl phenolpolyethoxy ethanol) 10 Xylene--- '15 The mixture is prepared in the samemanner as Example 5. v This emulsifiable concentrate is diluted withsufiicient water to drench the soil to the root zone of the plants andapplied to roses at a rate of 20 to 100 pounds active agent per acre.Excellent control is obtained of the dagger nematode (Xiphinemadiversicaudatum) allowing the roses to grow in a normal manner.

Example 7 Percent Thiodi(methanethiol) 5 Granular attapulgite clay 95The active ingredient is warmed to about 40 C. .and is sprayed over thesurface of the granular clay while the mass is kept agitated and isbeing tumbled in order to obtain a uniformly impregnated dry granularproduct. The granular product is applied to soil infested withpathogenic nematodes at rates of 20 to 100 pounds active agent per acreusing a conventional fertilizer spreader. The active agent is thenworked into the soil by disking. This treatment gives substantiallycomplete control of the sting nematode (Belonolaimus sp.) as shown by anematode count 15 days after treatment.

Example 8 Percent Methanedithiol 25 Blend of polyalcohol carboxylicesters and oil-soluble sulfonates Alkylated naphthalenes 69 The aboveingredients are blended until a completely homogeneous mixture isobtained. The resulting emulsifiable composition is extended with waterand sprayed at the rate of 75 pounds per acre of active ingredient in120 gallons of water on a field infested with sugar beet nematode(Heterodem schachtii') and the chemical is worked into the soil to adepth of 6 inches. Sugar beets grown in this field are substantiallyfree from nematode infestation.

Example 9 The wettable powder of Example 3 is diluted with micaceoustale to obtain a dust containing 2.5. active ingredient:

Percent Powder of Example 3 10 Micaceous talc The ingredients arethoroughly blended and deagglomerated until a uniform product isobtained. The mixture I is applied to the soil at the rate of 20 topounds of active ingredient per acre and is disked or rototilled intothe soil to obtain mixing into the zone of nematode infestation.

Example 10 7 Example 11 For the simultaneous control of root knotnematode and Pythium spp. and Rhizoctonia sppz, the mixture of Example 3plus commercial formulations of dimethylaminobenzenediazo sodiumsulfonate and pentachloronitrobenzene are prepared in a tank mix. Forthis mixture 40 pounds of the formulation of Example 3 is mixed with 80gallons of water. To this is added 7 /2 pounds of 70%pentachloronitrobenzene wettable powder and 10 pounds of 60%p-dirnethylaminobenzenediazo sodium sulfonate. This mixture is'appliedas a soil spray by application to bandsof soil with conventional sprayequipment. The application rate is 5. pounds per acre total activeingredient (equivalent to 100 pounds per acre in the treated band). Thesoil is rotovated immediately thereafter to mix the chemicals thoroughlywith the soil. Following this, cotton seed is planted in the treatedband. The cotton seedlings which develop are protected against root.knot nematode (Meloidogyne spp.) and the fungi Pythium spp. andRhizoctonia spp. A healthy stand of cotton plants is obtained and atharvest time an increased yield of cotton.

Example 12 Percent p-Dimethylaminobenzenediazo sodium sulfonate 15Thiocli(methanethiol) 20 Sodium lignin sulfonate 2 Dioctyl sodiumsulfosuccinate 1 Synthetic fine silica 20 Attapulgite clay 42 The abovematerials are thoroughly blended to prepare a uniform mixture. Themixture is then ground in a micropulverizer until the particle size issubstantially less than 0 microns.

This 35% wettable powder formulation is dispersed in water at the rateof pounds wettable powder per 10 gallons of water. This mixture is nowapplied as a soil spray by application to bands of soil withconventional spray equipment. The application rate is 3 /2 pounds totalactive ingredient per acre (equivalent to 70 pounds per acre in thetreated band). The soil is rotovated immediately after application ofthe spray, thoroughly mixing the chemicals with the soil. Immediatelythereafter, cotton seed is planted in the treated band. The cottonseedlings which develop are protected against root knot nematode(Meloidogyne spp.) and the fungi Pythium spp. resulting in a healthystand of cotton plants and an increased yield of cotton at harvest time.

The above ingredients are thoroughly mixed in a ribbon blender and themixture ground in a micropulverizer until the particle size issubstantially less than 50 microns.

This 30% wettable powder formulation is dispersed in water at the rateof 10 pounds wettable powder per 10 gallons of water. This mixture isnow applied as a soil spray by application to bands of soil withconventional spray equipment. The application rate is 3 pounds totalactive ingredient per acre (equivalent to pounds per acre. in thetreated band). The soil is rotovated immediately after application ofthe spray, thoroughly mixing the chemicals with the soil. Immediatelythereafter cotton seed is planted in the treated band. The developingcotton seedlings are protected against root knot nematode and the fungiRhizoctonia spp. A healthy stand of cotton plants is obtained and theyield of cotton at harvest time is increased.

The invention claimed is:

1. A method of controlling nematodes comprising applying to soil anem'atocidally effective amount of thiodi- (methanethiol) 2. A method ofcontrolling nematodes comprising applying to soil a nematocidallyeffective amount of methylenedithiobis (methanethiol) 3. A method ofcontrolling nematodes comprising ap plying to soil a nematocidallyeffective amount of thiodimethylene dithiobis (methanethiol) ReferencesCited by the Examiner UNITED STATES PATENTS 2,864,739 12/1958 Scottl6722 2,882,197 4/ 1959 Webb 167--22 2,938,827 5/1960 Wadsworth l67222,966,521 12/1960 Webb 167--13 2,998,346 8/ 1961 Scott l6722 3,103,4649/1963 Larson l6722 3,137,615 6/ 1964 Ichikawa et al 167-22 JULIAN S.LEVITT, Primary Examiner.

S. J. FRIEDMAN, Assistant Examiner.

1. A METHOD OF CONTROLLING NEMATODES COMPRISING APPLYING TO SOIL ANEMATOCIDALLY EFFECTIVE AMUNT OF THIODI(METHANETHIOL).